Show HN: Use TypeScript in Servo Browser Fork

Wasm exports are immediately available to TypeScript, even gc objects!

``` <script type="text/wast"> (module (type $Box (struct (field $val (mut i32)))) (global $box (export "box") (ref $Box) (struct.new $Box (i32.const 42))) ) </script> <script type="text/typescript"> const greeting: string = "Hello from TypeScript and Wasm!"; console.log(greeting, box.val); </script>